Means for automatically determining the angle of apparent climb or dive of a target



Jan. 30, 1951 H. K. WEISS 2,539,501 MEANS FOR AUTOMATICALLY DETERMINING THE ANGLE OF APPARENT CLIMB OR DIVE OF A TARGET Filed April 9, 1946 5 Sheets-Sheet l HERBERT K Weiss Jan. 30, 1951 H K WEISS 2,539,501

MEANS FOR AUTOMATICALLY DETERMINING THE ANGLE OF APPARENT CLIMB 0R DIVE OF A TARGET Filed April 9, 1946 5 Sheets-Sheet 2 Jan. 30, 1951 H. K. WElSS 2,539,501

MEANS FOR AUTOMATICALLY DETERMINING .THE ANGLE 0F APPARENT CLIMB 0R DIVE OF A TARGET Filed April 9, 1946 s Shets-Sheet s 3 1 vuc'wtom Jan. 30, 1951 2,539,501

H. K. WEISS MEANS FOR AUTOMATICALLY DETERMINING THE ANGLE OF APPARENT CLIMB OR DIVE OF A TARGET Filed April 9, 1946 5 Sheets-Sheet 4 HERBERT FHA/Eisewon 144;

Jan. 30, 1951 H. K. WEISS 2,539,501

MEANS FOR AUTOMATICALLY DETERMINING THE ANGLE 0F APPARENT CLIMB OR DIVE OF A TARGET Filed April 9, 1946 5 Sheets-Sheet 5 Snvcnfoc HERBERT K. Weiss UNITED STATES PATENT OFFICE MEANS FGR AUTOMATICALLY DETERMIN- ING THE ANGLE OF .APPARENT CLIMB OR DIVE OF A TARGET Herbert K. Weiss, Aberdeen, Md.

Application April 9, 1946, Serial No. 660,608

' 12 Claims. (01. 33-49) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 G. G. 757) I The invention described herein may be manufactured and. used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

With certain types of directors or computers used to compute the angle by which a gun should lead the gun-target line, a sighting reticle is provided that is rotatable in a plane perpendicular to the gun-target :line. During an engagement,

it is requiredto keep this reticle parallel to the apparent path of the "target in order that the director may supply correct angular output values of lead.

Assume that the path of the craft is extended indefinitely on both sides of the gun, and that a line is extended "from the gun normal to and inftersec'ting said path, extended if necessary, at a point commonly known :as the cross-over point.

ipoint divides the path into a so-called incoming leg on the side from which the target approaches, and an outgoing leg on the side on which the target departs. On the incoming leg, the target as viewed from the gun, appears to be climbing, while on the outgoing leg, it appears to be diving. Only at the aforesaid dividing Tpoin't does its path appear to be truly horizontal. Furthermore, the rate of apparent climb or dive constantly changes.

In order to simplify operation of the aforesaid type of directors, it is highly desirable that the reticle be rotated substantially automatically, to :remain parallel to the "apparent path of the tar- :get.

Itis therefore a purpose of the invention to provide a mechanism connected with such a reticle so as to automatically rotate the same at the proper rate necessary to maintain the reticle parallel to the apparent path of the target.

A further object is to provide a mechanism of the type mentioned in the preceding paragraph, in which the movements of the gun itself as it is trained and elevated to continuously engage the target, are combined and utilized to actuate the reticle :in the :proper manner.

Other objects and advantages will become apparent as the description proceeds.

In the drawings:

Figure '1 is a perspective view illustrating the optical illusionreierred to in the preceding paragraphs.

Figure 52 is aperspective view :used to illustrate the derivation of the relation between the rate of change :of the apparent angle of climb or dive, the :gun azimuth rate and the angle of elevation ofithe'gun,

Figure 3 is a schematic view supplemental to Figure 2, illustrating the relation between the rate of change of the apparent angle of climb or dive of the target and the gun azimuth and elevation rates.

Figure 4 is an elevation of one species of the mechanism for materializing the basic equation upon which the invention depends for operation.

Figure 5 is a elevation of the same species in a plane at right angles to the plane of Figure 4.

Figure 6 is an enlarged detail view of the resilient mounting of the planimeter-type wheel used to determine and transmit motion to the reticle.

Figure 7 is an enlarged sectional detail view taken upon a plane indicated by the line 'l--! Figure 6.

Figure 8 is a perspective simplified view showing the manner in which the instrument of Figures 4 and 5 may be associated with a gun.

Figure 9 is a perspective view of a modification of the form of the invention of Figures 4 to 8, inclusive.

Figure 10 is a sectional view taken on a vertical plane indicated by the line Ill-4 0, Figure 9.

Figure 11 is a section taken upon a plane indicated by the line 11-41, Figure 10.

Figure 12 is a perspective view of a second modification adapted more particularly for 'off carriage mounting.

Referring to Figure 1, the numeral 1 identifies a horizontal plane through a tracking point or gun station G, while the slant plane determined by the path 56 of the target and point G, is identified by the numeral 4. Planes I and 4 intersect in the horizontal line G8. A line 1 is drawn through a selected point of aim Tp on the target, lying in slant plane 4, and perpendicular to the line of aim from point G to point Tp. This line is not, in general, horizontal. Let #1 equal the angle between line I and a horizontal line through point 3 lying in the vertical plane through line I. This angle ,0 is, obviously, the apparent angle of climb or dive of the incoming or outgoing target. It is desired to find the relation between the rate of change of the angle 4/ and the gun rates and position in elevation and azimuth.

Referring to Figure '2, i represents the horizontal plane through the gun, and 9 the slant plane through the target and a line GT4 having any known azimuth, such as NS.

The slant plane 9 contains the line G'I connecting the gun and target position. A. vertical plane passed through GTp, intersects plane l in the line GT5T3. The angle TSGTp then .represents the angle of gun elevation and will be identified as E. Through Tp a plane TpT3T4 is passed perpendicular to line GT This plane intersects slant plane 9 in the line T Ti, and plane I in the line T3T4. The angle T T Ts then equals it, as explained in connection with Figure 1. The angle of train of the gun may be measured by T4GT3. This angle will beidentified as it. Since plane T4T3Tp wasconstructed perpendicular to GTp, the angle GTpT4 is a right angle, as are the angles GT3T4, T T3T4,' and GTpT3- A vertical plane is passed through point Tp perpendicular to line GT4. The trace of this plane on plane I, is T5Ts and its trace on slant plane 9 is TpTG. By construction, angle GTGTB is 90 and, since this plane is always perpendicular to line GT4, the angle TpT6T5, hereinafter identified as [3, remains constant.

The triangle GTsTs is similar to the' triangle GTsT4 since they each have a right angle and an angle in common othe'rth'an said right angle. Therefore,

T3T4 T5To' T3T4 QZ' 3 GT6 TET GT For a like reason, the triangle GTpT4 is similar to the triangle G'ITpT6 and Substituting (4) and (5) in 3),

cos B COS 6 cos p:

cos [1 orcos 1,0 cos e=cs 6 Cos B is constant, being always measured in a vertical plane through the target perpendicular to its horizontal path.

Therefore,

d/dt (cos ,0 cos E) =0 Differentiating In other words, the rate of change of the apparent angle of climb or dive of the target is equal to the product of the sine of the angle of gun elevation and the negative mm of movement of the gun in azimuth. 7

Figures 4 and show a ball type integrator capable of materializing Equation 10. A gear! is rotatably mounted upon any convenient base and is driven by a pinion I I and a flexible shaft I2, equally and oppositely to angular movement of the gun in azimuth. A sphere Iii is fixed to a shaft I5 defining a polar axis of said sphere. This shaft extends centrally and axially through a bail I3 and is fixed in gear I5. Bail I3 is secured against rotation relatively to support or by a bracket 45.

.Yoke I3 defines an axis I8 that forms an equatorial diameter 'of sphere I l, normal to the axis of rotation of gear Iii. A second yoke or bail I6 surrounds sphere It and is pivoted to pivotally mount a wheel H.

7 about axis I8.

trunnions 46 on yoke I3 for angular movement The outer portion of yoke It has upwardly-extending projections 25 and 22 shaped This wheel may conveniently be of the same diameter as sphere I4, and the dimensions are such that the periphery of wheel His in rolling contact with the surface 'of sphere I4."

' Figures 4, 5 and 6 show' a satisfactory method of rotatably mounting'wheel Ii. From Figure 4 it will be noted that projections 2i and 22 are slotted as at '23, Figure 6, to slidably receive the ends of shaft 2 upon which wheel H is fixed.

An adjusting bracket 26 is attached to the upper endof projection 22, as by means of screws 2? to form therewith a continuation of slot 23. A bearing 'block'25 is shaped to fit over the top surface of shaft 24'. This block is guided for vertical sliding along slot 23, by lugs 28 slidably fitting'vertical channelsformed in the portion -of projecti0n'22 forming slot 23'. 'A pressure block 2'9 is'slidably mounted in slot 23, similarly to block25. "Blocks 25 and 29 are urged apart by "a coil spring 3%). ed into bracket 26, so" that its end bears upon An adjusting screw 3| is thread- I projection 2i mountsa bearing for shaft 24 that is a duplicate of the onejust described and shown at Figure 6. Thus, Wheel I1 is at all times firm- 'ly urgeclinto contact with sphere I4 so as to roll thereon substantially Without slippage when yoke I6 is pivoted about axis I8 to a position such that the point'of contact betweenwheel It and sphere I 4 is removed from the point of intersection of the axis 'of shaft I5 with the sphere.

Projection 2i may carry a bracket 32, secured thereto by screws 33, and providing for a connection 35 for the sheathing of a flexible shaft .34 so that rotation of wheel I! effects a corre- 1 segment 38 fixed to bail I3 concentric of axis I8. Segment 38 and bracket 32 may act to place the bail I6 insubstantial balanceabout the axis I8.

. Pinion 35 is connected for rotation by a flexible shaft'39 havinga coupling 40' for connecting the sheathing of shaft 39 to extension '31. Thus, on

I s the axis- I3.

rotation of pinion 36, bail It is rotated about The angular extent of segment 38 is sufiicient to provide for a little more, than of rotation of bail It so that, for example, shaft 24 may rotate from a substantially horizontal position to a substantially vertical 'one.

If desired, counterweights 4i and 4| may be mounted upon bolts 42 and 4'3 carried respectively by extensions 3'! and M of bail iii. In this way, the bail and parts carried thereby may be substantially balanced about axis is to there- 'by assure smooth and accurate operation.

The model just described is intended for on carriage mounting. That is, support 44 is a part of, or rigidly secured to, the gun carriage with yoke l3 so positioned that axis 13 is at all times parallel to the gun trunnions. Flexible shaft I2 is, then, connected to be driven by the training mechanism of the gun so that sphere i4 is rotated equally and oppositely to the movement of the gun in train. In this manner, the sphere is fixed against rotation relatively to the cardinal directions. Flexible shaft .39 is connected to be operated by the elevating mechanism of the gun, so that, for example, the axis of shaft 24 is maintained parallel to the axis of the gun bore. As previously explained, flexible shaft 34 is connected in 1:1 relation with the sighting reticle positioned in the line of sight of the sighting device and rotatable a plane perpendicular to said line of sight. Thus wheel H and the aforesaid reticle are rotated proportionally to the rate of movement of the gun in azimuth, multilied by the sine of the angle of gun elevation.

The negative sign in the right hand side of Equation indicates that the rotation applied to sphere it is opposite to the training movement of the gun.

Figure 8 shows the manner in which the 'instrument of Figures 4 and 5 may be associated with a gun. The gun platform 53 is supported upon base is for rotation about a central vertical axis defined by pivot 55. Parallel supports 52 and 53 are fixed to platform 59 and provide bearings for trunnions, one of which is identified at 54. These trunnions project from gun cradle 48 and define a normally horizontal elevation axis for barrel ii. Training of the gun is effected by turning of a handwheel 55 connected through shaft 55, gearing 5i, shaft 58, with a pinion 59. Einion 59 is inmesh with a fixed rin gear 58, only a small portion of which is shown.

A bracket 5! is attached to support 53 and carries the resolver unit of Figures '4 and 5, previously described. It is therefore sufficientmerely to identify gear i3, sphere i i, yoke 18, wheel ll, bracket 55, and flexible shafts l2, 3 and 35..

Flexible shaft i2 is connected to be driven by a pinion attached to shaft 58 :and in mesh with a reversing idler 63. idler meshes with a pinion 56 directly connected to the core of shaft if. The connections and gear ratios are such that the sphere is rotated relatively to the gun, equally and oppositely to the guns rotation. In other words, the sphere is maintained angularly fixed in a. uth. For ease in understand ing, Figure 8 sho '5 axis 58 coincident with the axis of trunnions This position is not essential. In fact, the axes 'of shaft trunnions 135- and shaft i i, may have any angular relation relatively to the *ain and elevation axes of the gun, .so long t ir relation to each other is as shown at Figures '5.

Elevation of the gun d! is effected by rotation of handwheel connected'by reduction gearing, not shown, to drive .a shaft This shaft is journaled at one end in support 152 and carries pinion ii; .at its inner end, in mesh with the elevation gear segment 5d, secured to the 6 under side of cradle 48, concentric of the axis of trunnions 54, in the manner well known in the art. The flexible shaft 39, has one end connected to shaft 66 to be driven thereby and its other end attached to pinion '36,"Figure 5, as previously explained. The gear ratios are such as to cause the yoke 6 to rotate about axis IS in synchronism with the elevation of the gun and, for simplicity of explanation, it is assumed that the axis of shaft 23 remains parallel to the gun bore.

Rotation of wheel 11 as a result of training or the gun while elevated, is transmitted over flexible shaft 34 to one side of a differential 69 having its center connected to drive a ring gear 10 having reticle i! mounted diametrically thereof. 'Gear 10 is shown as rotatably mounted within the casing of a telescope 12. This casing may have a circumferential slot of an extent sufficient to enable engagement between gear 19 and the center of differential 69. The other side of this differential is connected for manual operation by a handwh-eel E2. The gear ratios are such that gear H3 and wheel i! rotate in synchronism. Reticle it therefore rotates in accordance with Equation 10 and, after initial adjustment of the reticle by wheel 12, the reticle remains parallel to the apparent path of the target for the assumed conditions of flight of the target.

At Figure 9 I have shown another form of the invention using a ball-type integrator. In this form, the gun E5 and cradle I5 are mounted as before upon trunnions 11 carried in supports 18. A bearing 79 is secured to the side of cradle I6 and journals a shaft 80. A lever arm 8| is fixed to shaft 89 and has its lower end pivoted at 82 to an end of link 83. The other end of link 83 is pivoted at 84 to right-hand support 18 and the dimensions are such that the points of intersection of the axes of trunnion Tl, bearing 19 and pivots 82 and 84, with a plane normal to said axes, lie at the vertices of a parallelogram. As the parallelogram side thus defined by TI-84 is v rtical, link 8: is maintained in the vertical position.

At its outer end, shaft carries a bracket 84' in which a shaft 85 is journaled. The parallelogram arrangement previously described, acts to maintain the axis of shaft 85 vertical. This axis coincides with the polar diameter of sphere 86. Furthermore, the parts are so dimensioned that the axis of shaft 3!], extended, coincides with a diameter of the sphere normal to the aforesaid polar axis. The lower end of shaft 85 has a gear 81 fixed thereto and in mesh with a pinion 88 connected to be driven by gun training hand- .wheel 85, through flexible shaft 99. Training is effected through conventional gearing, not shown, operated by shaft 9! and cting between rotatable platform 92 and fixed base 93. As in the instrument of Figures 4-8, the gear ratios and connections are such as to rotate sphere 86 equally and oppositely to the rotation of platform 92 whereby the sphere remains angularly fixed in azimuth as the gun is trained.

A bracket 9 is fixed to cradle 16 and is formed with spaced parallel arms 95 and 85 whose outer ends form bearings for the support of a rotatable shaft 9? (Fig. '10). A handwheel 98 is fixed to one end of shaft iii. A pair of composite gears 99 and I50 are journaled upon shaft 91. Each has a respective bevel pinion IOI and ma positioned within a sleeve ms and forming two sides of a difierential, indicated generally by the numeral N34. The center of differential i0; is

Y having its rotor connected with shaft I2I.

As best shown at Figure 11, sleeve I63 has a .second sleeve I96 secured in parallel offset relation by a connecting portion I 61. journals a shaft IIl'I having a gear I68 attached Sleeve I 6-6 to one end and planimeter-type wheel I63 attached to the other end. Gear I68 is in mesh with gear I06. Still referring to Figure 11, bracket 94 has an arm I I!) attached thereto, with its outer end extending beneath sleeve 566. A coil spring I I I has one end attached to the under side of sleeve I66 and its other end secured to 'an adjusting screw H2. Thus spring II I acts to hold wheel I69 in contact with sphere 86 with a force that may be adjusted by operation of nut I I3 so that the wheel rolls upon the spherejsubstantially without slippage.

The parts are so related that wheel I63 at all times lies in, and

rotates in, a plane containing the axis of shaft 86. The reticle I I4 may be formed upon a trans-=-' parent plate rotatable within a frame H5 which may conveniently be attached to bracket 94. The plate has a rim, not shown, formed with teeth,

meshing with a gear H6. This gear is fixed to is imparted to reticle i I4 by way of gears I63,

I66, I62, I65, Illl, 59, Ill and IE6 as and for the purpose fully explained in connection with Fig ures 4 to 8, inclusive.

Figure 12 shows \a, form of the invention suitable for mounting off the gun carriage. Basically, the instrument comprises a frame -I2fi having a main section in which is journaled a shaft I2I having a disc I22 fixed to its upper end. A bracket I23 depends from frame I26 and carries a repeater I24 such as a conventional Selsyn or Autosyn Repeater I24 is electrically connected for control by a transmitter at the gun (not shown). This transmitter is so driven that disc I22 is rotated in synchronism with movement of the gun in shaft I25 and rod I26. A driven wheel l28 slidably fits shaft I25, for rotation therewith and fits snugly between the arms of slide I21. The wheel I28 is thus guided for movement radially of, and in contact with, disc I22.

Slide :2? has a bar E25 fixed thereto. This bar is parallel to disc I22 and has a slot I33 at right angles to the axis of shaft 925. A'repeater 32 ismounted upon a bracket I33 and has its rotor attached to one end of a shaft I35. may conveniently be co-axial of shaft I2i. lever I 34 is attached to the lower end of shaft J3! and has a pin I35 at its outer end. This pin sliclably fits slot I36 and its radial distance from {the axis of shaft I3i is such as to move wheel 128 adjacent the rirnrof disc 422, when leverI34 is parallel with shaft I25. displaced from the center of disc I22 by a distance proportional to the sine of the angle of rotation Thus, wheel I2 6 .is

of lever I34 from an initial position perpendicular toshaft I25: Rotation of lever I34 is effected This shaft by repeater motor I32 under-thecontrol of a transmitter, not shown. It will be. understood, however, that this-transmitter is positively driven by the gun elevating mechanism so that lever I34 .rotates in synchronism with movement of the gun-in elevation. In short, when the quadrant elevation of the gun is zero, lever I34 will be perpendicular to shaft I25 and wheel E28 will be positioned at the center of disc I22. When quadrant elevation is 90 lever I34 is parallel with shaft I25 and wheel I28 is'driven by disc I 22 at maximum speed ratio. Thus it will be clear that shaft 25 is driven at a speed proportional to the product of the gun azimuth rate and the sine of the angle of gun elevation.

Shaft E25 is connected to the rotor of a transmitter I36. This transmitter has its casing and stator journaled upon frame I26 for independent rotation about the axis of shaft I25. Manual rotation of the stator may be effected by rotaton of a pinion I3'I, in mesh with a ring gear I38 affixed to the aforesaid casing; A handle I39 is secured to pinion I38. Electrical connections are made to the transmitter by slip rings I46 and brushes I4I, carried by an insulating rod I42. Conductors I43 lead from brushes IM to a repeater I44 whose shaft has a pinion I45 in mesh with a ring gear I46. A sighting reticle I4! is mounted diametrically on gear I46. This reticle and gear may be interposed in aline of sight device, such as a telescope, in the manner described in connection with Figures 8 and 9. Such a sighting device may be directly carried by the gun or its cradle. Alternatively the sight of the species of Figure 12, may be that of a director remote from the gun. In all cases, the angular movement of the reticle may be conveyed by mechanicalor electrical repeater means to a director and there utilized as one factor in determining the angleby which the gun should lead the line of sight in order effectively to engage the moving target. Since obviously,

a repeater I44 may be actuatedeither by rotation of the rotor .of transmitter I36 relatively to its stator, or by rotation of its stator of. I 36 relatively to its rotor, initial adjustment of reticle I41 may be effected by turning of handle I39. In this respect the transmitter I36 is the full functional equivalent of the differentials 69 and IE4, Figures 8 and 9, respectively.

Thus it will-be seen that I have produced an instrument that is relatively simple to construct, while being positive and mathematically accurate in theory and operation. Furthermore, after initial adjustment, and so long as the target maintains a straight course, the operation is automatic andthe instrument is correctly adjusted by movements of the gun itself.

While I have shown several forms which my invention may take, modifications and substitutions of equivalents will readily occur to those skilled in the art. Consequently, I do not wish to be limited tothe precise details of construction. To the contrary, it is my desire that the foregoing disclosure be taken in an' illustrative sense only and to reserve all such changes, alterations, modifications and substitutions as fall within the scope of the subjoined claims.

Having now fully disclosed the invention what I claim and desire to secure by Letters Patent is: 1. The combination with a gun having a sight defining a line of sight toatarget said sight having a reticle transversely of and rotatable about 7 said line of sight as an axis, and means responsive to the movement of a gun in elevation and train connected to so rotate said reticle in accordance withthe' equation d lf=-sln'd, where 11 is the rate of reticle rotation, e is the angle of gun elevation, and do is the rate of movement of the gun in train.

2. In combination with a gun mounted for angular movement about mutually normal train and elevation axes, of a sight carried by said gun for movement therewith, said sight having a sighting reticle transversely across and rotatable about the line of sight thereof as an axis, and means responsive to the movements of said gun in train and elevation, and connected to so rotate said reticle at a rate proportional to the rate of movement of the gun in train multiplied by the sine of the angle of gun elevation.

3. In aninstrument of the type described, a driving member rotatable about an axis, means for so rotating said member at a rate proportional to the rate of train of a gun, a wheel in rolling contact with said member, means responsive to the angle of elevation of said gun for moving said wheel relatively to said member to maintain the point of contact of said wheel with said member at a distance from said axis proportional to the sine of the angle of elevation of said gun, a sighting reticle rotatably mounted upon said gun, and a driving connection between said wheel and reticle for rotating the latter.

4. In combination with a sight adapted to establish a line of sight to a target and having a reticle defining a line transversely of and rotatable about said first-mentioned line as an axis, a sphere, a stationary yoke having bearing means defining a first axis diametral of said sphere, a. bail journaled in said bearing means for pivotal movement about said first axis, a wheel journaled in said bail for rotation about a, second axis normal to said first axis, said wheel having its periphery in contact with said sphere and lying in a plane containing said first axis for all positions of said bail about said first axis, and a driving connection between said wheel and said reticie.

5. In combination with a gun mounted for train and elevation about mutually normal axes and having a line of sight device including a reticle defining a line trans'-Jersely of and rotatable aboutsaid line of sight as an axis, a sphere, a yoke, means mounting said sphere and yoke for relative rotation about a first axis diametral of said sphere, said yoke having bearing means defining a second axis diametral of said sphere and normal to said first axis, a bail jour naled in said bearing means for rotation about said second axis, a wheel journaled in said yoke for rotation on an axis normal to said second axis, said wheel lying in a diametral plane of said sphere containing said second axis, and having its periphery in contact with said sphere, and a driving connection between said wheel and reticle.

6. A computing gun sight comprising, a sphere, a yoke, means mounting said sphere and yoke for relative rotation about a first diameter of said sphere, bearing means carried by said yoke and defining an axis coincident with a second diameter of said sphere normal to said first diameter, a bail journaled in said bearing means for pivotal movement about said axis, a wheel having the same diameter as said sphere and journaled in said bail for rotation in a plane containing said second diameter, with its periphery in contact with said sphere, means effecting relative rotation of said yoke and sphere about said first diameter by and proportional to the change in azimuth of a gun, means cilecting relative rotation of said yoke and hail about said second diameter by and proportional to change in elevation of said gun, a sight having a reticle rotatable about the line of sight determined by said sight, a differential having one side connected to be driven by said wheel, and a second side connected to rotate said reticle, and manually-open able means connected to drive the third side of said difierential, whereby initial manual adjustment of said reticle may be efiected.

7. In combination with a gun having a cradle mounted for movement about mutually-normal train and trunnion axes, a shaft pivoted on said cradle on a first axis parallel to said trunnion axis, a bracket secured to said shaft, a sphere journaled on said bracket for rotation about a.

second axis, said first and second axes being coincident with respective, mutually-normal diameters of said sphere, means connected with said shaft to maintain said second axis in fixed relation with the vertical as said gun is elevated, means responsive to training movement of said gun to maintain said sphere fixed in azimuth about said second axis, a sighting reticle carried by said cradle and extending transversely of and rotatable about a parallel to the bore of said gun, a line wheel carried by said cradle and rotatable in a plane containing said first axis, said wheel being in driven contact with said sphere, and a driving connection between said wheel and reticle whereby the latter is rotated at a rate equal to the rate of train of said gun multiplied by the sine of the angle of gun elevation.

8. In a computing sight for a gun mounted for movement about mutually-normal train and elevation axes, a sphere carried by said gun and rotatable about mutually-normal first and second axes parallel, respectively, to said train and elevation axes, means connected with said sphere to maintain said first axis vertical for all angles of gun elevation and to rotate said sphere about said first axis to maintain a given diameter t' erect fixed in azimuth for all angles of train of said gun, a reticle carried by said gun transversely oi. and rotatable about a line of sight substantially parallel to the bore axis of said gun, and means driven by relative rotation of said gun and sphere for rotating said reticle at a rate proportional to the rate of train of said gun times the of the angle of gun elevation.

9. In combination with agun sight having a reticle defining a line transversely across and ro tatable about the line of sight of said sight, a bracket adapted to be fixed with said gun {or elevation and train therewith, a pair of connected spaced parallel first and second sleeves, a first shaft journaling said first sleeve in said bracket, a second shaft journaled in said second sleeve, a Wheel and a first gear fixed to respective of said second shaft, a difierential mounted on said first shaft and including second and third gears secured to the respective sides of said differential, said first and second gears intermeshing, a drive from said third gear to said reticle, manually operable means connected to drive the center of said differential through said first shaft, a sphere adapted to be mounted on said gun for rotation about a vertical polar axis, and means urging said second sleeve about the axis of said first shaft to bring said wheel into yield ing contact with said sphere, whereb the of contact of said wheel on said sphere traverse,-. a meridian thereof as the gun is elevated.

10. The combination with a rotatable reticle adapted for mounting within the field or" view a gun sight, a disc rotatabl about a first axis, a

11 splined shaft rotatable about a second axis normal to and concurrent with said first axis, a wheel on said shaft for rotation therewith and sliding therealong radially of, and in contact with, said disc, a first repeater motor connected to rotate said disc in response to training movement of a gun, a second repeater motor connected, in response to changes in the angle of I elevation of said gun, to move said wheel a radial distance from the center of said disc, proportional to the sine of the angle of gun elevation, a transmitter having a rotatable rotor and a rotatable stator, means connecting said shaft and rotor for conjoint rotation, manually-operable means for rotating said stator, a third repeater connected for actuation in response to relative rotation of said rotor and stator, and a driving connection between said third repeater and said reticle.

11. The combination with a reticle rotatable within the field of view of a line of sight device about the optical axis of said device, first and second aligned shafts, first and second repeaters connected to rotate said shafts, respectively, a disc fixed to said first shaft, a lever fixed to said second shaft, a slide mounted for translation only in one direction radially of said disc and having a slot normal to said one direction, a wheel journaled in said slide on an axis parallel to said one direction and in engagement with said disc,

a pin on said lever slidably engaging said slot, an electric telemetric transmitter having a rotatable stator and rotor, a driving connection between said wheel and said rotor, manually-operable means for rotating said stator, and a repeater connected to rotate said reticle in response to relative rotation of said stator and rotor.

12. In combination with a gun mounted for angular movement about mutually normal train and elevation axes, a sight carried by said gun for movement therewith, said sight having a reticle extending transversely across and rotatable about the line of sight of said sight as an axis, rotatable means, means rotating said rotatable means in response to movement of said gun in train, wheel means in driven contact with said rotatable means and responsive to movement of said gun in elevation and to operation of said rotatabl'e means, and a driving connection between wheel means and reticle whereby said reticle is rotated at a rate proportional to the rate of movement of said gun in train multiplied by the sine of the angle of gun elevation.

HERBERT K. WEISS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,962,590 Haubroe June 12, 1934 2,372,613 SVObOdfi Mar. 27, 1945 2,396,701 HOlSChLlh et a1. Mar. 19, 1946 2,405,383 Wackett Aug. 6, 1946 

